Phoenix coach Ernie Merrick has blasted Football Federation Australia for not providing sideline dugouts across all A-League venues.

Under pressure Sydney FC coach Frank Farina had a drink thrown on him by a disgruntled fan last Saturday during the 3-0 home loss to Adelaide United at Allianz Stadium.

Merrick has coached in the A-League since its inception in 2005 and, without going into specifics, said it was naive to think the Farina incident was the first time the safety of a coach or player had been threatened.

Merrick said Westpac Stadium was the only venue that uses dugouts and they were doing so against FFA orders.

Other clubs use uncovered chairs on the sideline.

Merrick said most A-League supporters were fantastic but "there's always one or two that are out of order".

"And we should be not be exposed, any coaches, doctors, physios, players, shouldn't be exposed to sitting two metres from the fans, with some of their behaviours," Merrick said.

"It's a security issue and on top of that an environmental issue as well. I mean there's nothing more ridiculous than us sitting on $5 white plastic BBQ chairs, in the howling wind and rain, with umbrellas over our heads, trying to coach a game or being prepared to come on. I mean we'd be the only country in the world that's doing that."

The FFA has said that all A-League venues will have dugouts from next year but Merrick said the safety issue had been dodged since 2006.

"Let's be sensible, a little bit of security and safety and a shelter from the environment is such a good thing. But let's not pretend that one incident is the only incident that occurred, against Frank Farina. And Frank shouldn't have to deal with that, none of us should."

Meanwhile, key Phoenix midfielder Albert Riera will miss Sunday's home game against Melbourne Heart as he awaits further scans on his groin tear.

Riera also missed last Sunday's 3-2 win over the Jets in Newcastle.

"He's unable to play this week and I think he'll be out for a couple of weeks, but we don't know the details yet."

Leo Bertos is also likely to miss the Heart match with his own groin injury but Michael Boxall and Kenny Cunningham are set to return from suspension to the starting XI.